Generally a chair has a backrest portion and is also referred as a backrest chair. A chair generally comprises two side frames, a seat portion fixed between the two side frames and a backrest portion disposed between the two side frames and above the seat portion. In the prior art, the backrest portion of the chair is fixed to the two side frames by welding or utilizing fasteners. With this fixing method, welding or utilizing fasteners will make the assembling operations complicated and inconvenient. In addition, the welding seams or the fasteners are exposed to the outside and thus can be observed from behind, which adversely affects the appearance of the chair.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.